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Study finds bird declines in mountains of Finland, Sweden, Norway

Yereth RosenAlaska Dispatch News

Bird populations in the mountains of Finland, Sweden and Norway are declining, a trend associated with changing weather transforming northern forests, a newly released study says.

The study, conducted by scientists in the three countries and published online on Dec. 2 by the Journal of Avian Biology, said nine of 14 common bird species in the Fennoscandia mountain range of northern Europe showed significant declines from 2002 to 2012.

“As these declines were synchronous in all three countries and occurred both in tundra and birch forest, one may suspect that they were driven by the same large-scale phenomena,” the study says.

The finds of “substantial” declines over the last 11 years are “in line with the predictions based on climatic forecasting suggesting that ... species in Fennoscandia will likely show declining population sizes and reduced range sizes in the future,” the study says.

The study is touted by the authors as the first presentation of population trends for the common mountain birds that covers the whole Fennoscandia mountain region.

The bird declines coincided with increases in summer heat and rain during the period, compared to the previous 40 years, scientists said. The population drops were more marked among resident birds, like willow and rock ptarmigan and short-distance migrators, indicating that whatever is causing the birds’ declines is something happening nearby within the Fennoscandia mountains, not in their southern wintering grounds.

Along with changes in regional weather patterns, other factors were proposed in the study as potential contributors to the decline -- including changes in the composition of the forest, where pine growth is spreading uphill and starting to displace birch. The spread of insect pests, which could have an effect on birds since some of the insects provide food, could also be a factor.  

Meanwhile, a separate Canadian study appears to let two Northwest Territories diamond mines off the hook for a decline in reproductive success of falcons nesting nearby. The study, published in the current edition of Avian Conservation and Ecology, found that a decline in hatch success for peregrine falcons and gyrfalcons near the Ekati and Diavik mines matched declines found for Canadian falcons far away from any industrial development.

The observed hatch declines seemed to have nothing to do with mine activities or expansion, and “may be in response to natural environmental conditions occurring at larger geographic scales,” the study says.

Contact Yereth Rosen at yereth(at)alaskadispatch.com